Bend Strength of FRP Stirrups: Comparison and Evaluation of Testing Methods
Publication: Journal of Composites for Construction
Volume 14, Issue 1
Abstract
This paper provides a comparison and evaluation of the current test methods used to determine the strength of fiber-reinforced polymer (FRP) bent bars/stirrups at the bend location (bend strength). The available methods depend on applying tensile forces through the straight portion of the bent bar/stirrup and keeping the bend zone restrained to generate a stress perpendicular to the bend direction in addition to the stress in the longitudinal direction. This could be achieved through the ACI 440.3R-04 B.12 test method for U-shaped bare FRP bars. Another possible method is the ACI 440.3R-04 B.5 which evaluates the bend strength of FRP stirrups by embedding them in two concrete blocks, which are pushed apart until the rupture of the FRP bent bars. Both methods were employed in testing FRP stirrups and bent bars and the bend strength was compared. The test results showed that the ACI 440.3R-04 B.12 test method consistently underestimates the bend strength of FRP stirrups. On the other hand, B.5 test method is more reliable and representative to the actual state of stresses in real concrete structural elements.
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Acknowledgments
The writers wish to express their gratitude and sincere appreciation to the Natural Science and Engineering Research Council of Canada (NSERC), Pultrall Inc., (Thetford Mines, Québec, Canada), and The Ministry of Transportation of Quebec (MTQ) for financing this research work. The writers would like to thank the technical staff in the structural laboratory at the Department of Civil Engineering, University of Sherbrooke (Sherbrooke, Quebec, Canada) for their assistance in fabricating and testing the specimens.
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Information & Authors
Information
Published In
Journal of Composites for Construction
Volume 14 • Issue 1 • February 2010
Pages: 3 - 10
Copyright
© 2010 ASCE.
History
Received: Dec 17, 2008
Accepted: May 29, 2009
Published online: May 30, 2009
Published in print: Feb 2010
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